Introduction: Sumo-Bot (TSA and Science Olympiad Rules)
This is my Sumo-Bot for my Technology Students Association (TSA) club http://www.nystsa.org/ . This robot also fits in with all Science Olympiad rules as well. Basically for the event you have to build a sumo bot that fits all of the requirements of the rules and compete the robot against other robots. to start the match you have to first prove that your robot can move my moving out of your box and hitting a tennis ball, then you are allowed to start to go after your competitor. The first robot to completely push the other robot out of the black ring wins. the bouts are 2 minutes long, if there is a tie or time runs out the lightest smallest robots wins. the robots can weigh up to 2 kilograms or about 4.4 pounds. and they have to fit in 40cm x 40cm x 40cm box. after reading all of the rules I realized that we needed to make the bot as small and as light as possible so if there is a tie, i win. i also realized that if my bot was that small we needed to have and offensive and defensive weapon (sort of). but since we cant have weapons i had to go with a plow that can actuate and possibly pick up other robots. since our robot is going to be small and light we need to be able to get out of danger really fast. so i had designed a robot that has a actuating plow, is very small, very fast and very light. This instructable will go through my process of designing and constructing my sumo bot.
( just a note this instructable was made after my competition for TSA and my robot got first place and was the lightest and strongest robots. so all of the pictures will be of parts that were made and not being made).
Step 1: Materials
For materials I used
4 X micro metal gear motors with 100/1 gear ratio http://www.robotmarketplace.com/products/IL-GMS100.html
1 X sabertooth 5 amp dual motor controller http://www.robotmarketplace.com/products/0-SABER2X5-RC.html
1 X Track set http://www.robotmarketplace.com/products/IL-TKT1.html
2 X 2 channel 2.4 gigahertz TX and RX ( got them from old RC cars)
2 X High torque metal gear servos http://www.robotmarketplace.com/products/0-HRC32645S.html
4 X PC standoffs from radioshack
1 X 1000 mAh 7.4v LIPO battery http://www.robotmarketplace.com/products/0-PE10002S-20C.html
1 X 1100 mAh 7.2v NiMh (from old LOSI rock crawler)
1 X speed controller (from old LOSI rock crawler)
1 X signal doubler http://www.performance-hobbies.com/
1 X sheet of acrylic
some velcro tape
2 feet of .5 X .5 right angle aluminium
some spare sheet metal
5.5in X 3.5in X 1in aluminium block ( for chassis)
Step 2: Chassis
So for this part you will need a CNC machine or you can just buy this chassis( note: this chassis comes with all of the motors and tracks and hardware and comes with a acrylic top, but this chassis is smaller than what i am making so you will just ave to account for that in the measurements. but all i am doing is just making that chassis wider and taller)
If you have access to a CNC machine then great and you can mill out your chassis. mine took about 7.5 hours to complete.
this is the drawing that i used to make my chassis. but you have to change a couple of things
this drawing was found at http://www.robotmarketplace.com/products/IL-ANTKIT2.html
int the second picture you can see the size difference. on the left is the one I bought from the robot marketplace and on the right is the one that I made. you cant see it from this angle but there is also a big height difference as well
Step 3: Upper and Lower Deck
On my sumo-bot I wanted it to look really cool and I needed a place to put my drive battery. so I made my robot with two decks. the lower deck holds my drive battery and the two receivers. it also has holes in it for wire to come up from the sabertooth motor controller. The upper deck holds my two plow servos and their battery as well as most of the wiring. the upper deck also holds the motor controller that we will use as a voltage regulator for the servos. the two decks are separated by the 4 PC standoffs. this 2 deck design really help to make everything compact so we can keep the size down. and plus it looks cool. To make the decks I used some acrylic sheet that I had lying around in my basement. the bottom base is the exact size as the top of my robot and all I did was put my robot on the sheet and traced my robot on it and then cut it out and sanded it so it fit perfectly. after I cut it out and it fits I drilled the holes for the top to screw onto the chassis with 4X, 4-40 screws. these holes are shown in the drawing in step 2. To paint the lower deck I used some sandpaper and roughed up the top of the deck, so the paint has something to stick to. then with some acrylic paint I painted the top a flat black and painted the sides blood red. I painted the top the same thing as well. to make the top deck I placed my two servos and with my 1100mAh NiHm battery in between them on a sheet of acrylic and then traced that but then traced them again this time adding half an inch to the outside to make the trace much bigger. then I cut the bigger trace and sanded it to size. much of the extra half inch the we added on will be cut off just to keep the size and weight down. then i sanded it and painted it just like the lower deck. in a later step we will drill the holes for the PC standoffs and the servo mounts. the first picture is the lower deck and the second pic is the upper deck.
Step 4: Servos, Mounts and Plow
Our robot is has a pretty power full drive-train with 4 X 100-1 metal geared motors. but it is not as powerful as the much larger robot that weight 4 pounds. so we need to defend our selfs. the rules say no weapons so we can't hurt the other robots. so to protect the robot we need a plow. its not a weapon and it is what every other robot has. the only difference will be that ours is actuated and can lift up other robots. this has proven to be very successful. it how my robot got first place and the others didn't. the plow will be designed to lift up the other robots so their wheels or mode of transportation is useless and cant get traction on the mat. then we will push their robot off the mat. the plow has to lift a lot of weight and cant bend or weigh to much. to make my plow move I have two high torque metal geared servos that are opposite of each other. the plow will have to arms that attach the plow and the servos together. since the servos are facing opposite of each other we need a signal doubler to double the signal the two servos. the last picture is the signal doubler. it has one input and two output. one output is doubled and fed to both servos. now it will all depend on the servos that you get, to build the servo brackets, but they way I did it was I took the .5 X .5 right angle aluminium and bent it and cut it so it made perfect brackets. you can see them in the pictures. the plow that i made was made out of some metal that I took from an old computer case. it has all of the holes already cut into it for air circulation for the computer. all I did cut it, bend it, and paint it. it works perfectly. To power the Servos I am using a old Electronic Speed Controller to regulate the power going to the servos. this works very well and it is held on with velcro on the right servo.
Step 5: Drive Train
For the drive train of my sumo-bot i went with 4 100:1 Mini Metal Gear Motor they offer great amount of torque and speed. if you want more torque then get the 298-1 ratio motors. if you want speed get the 50-1 ratio motors. to power the motors I am using a sabertooth 2 X 5 amp dual motor driver. it drives all 4 motors with 5 amps to each side. it also differential drive so it mixes the signals for you. to power the motors and the drivers. I am using a 1000 mAh LiPo power edge battery. this will drive the motors for a long time
Step 6: Locomotion
To move the robot I am using tracks. Tracks get more traction than wheels and they are cooler than wheels. they come in a nice kit and fit perfectly on the motors that I got. you can use wheels but tracks are just all around better.
Step 7: Wheelie Bar
After building the bot and testing it for a little bit. I realized that I needed something to keep me from flipping over when I lifted heavier robots. So I made a Wheelie bar out of the Right angle aluminium and sanded the bottom down on a disk sander so it is nice and smooth. Now when I pick up heavier robots I don't flip over my back just lifts up a bit.
Step 8: Finished SUMO-BOT
Once you have don all of this you can create a very functional robot that is very small, fast and weighs almost nothing. my sumobot only weighs 1.2 pounds and can lift about 6 pounds. I was able to lift robots 5 times my weight and 3 times my size.
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